(1) Field of the Invention
The present invention relates to a color image forming apparatus capable of inputting image information such as a color original etc., by color separation, and more particularly relates to a color image recording apparatus which stores color-separated image information in rotary-type storage media such as hard disks or the like, and reads the image information stored in the rotary-type storage media so as to transfer the data to the image recording section and reproduce the color image.
(2) Description of the Prior Art
In a color image forming apparatus, for example, a digital color copier, the image of an original captured by the scanner is subjected to predetermined image processings, and then is output as a color copy from the printer unit. In the field of digital color copiers, it is necessary to provide products which make the best use of colors and digital features.
Because of such demands, recent digital copiers tend to have a configuration in which the image of a color original is stored into the memory so as to modify the color image into a richer representation, or tend to have high performance configurations with many editing functions such as editing a plurality of color images in parallel.
For example, Japanese Patent Publication Hei 1 No. 45,632, discloses a color image forming apparatus with which the image of a color original is separated in color and read by a color CCD and the thus captured color-separated images of the color original are stored into the memory, then the data is sequentially read out therefrom to reproduce a color image through the recording portion.
In accordance with the color image forming apparatus written in this disclosure, color-separated images of the color original picked up by the color CCD are temporarily stored in buffer memory for individual colors. Then, the thus stored color-separated sets of image information are successively read from the buffer memory and are input to the semiconductor laser, which, based on the color-separated sets of image information, reproduces toner images of different colors on respective photoreceptors. Finally, the images of the different colors are superimposed on the copy medium on the transfer drum, thus producing a color image.
In view of the above configuration, the remaining sets of color image information other than that currently engaged for recording need to be stored until they can be used. Therefore, the buffer memory in which each color set of color-separated image information is temporarily stored needs a memory capacity at least equal to the amount of data of the maximum copy size (e.g., A3). Further, in order to produce a correct reproduction from a color original, the scanner portion for scanning the original needs to be developed into a high resolution one.
The color image information picked up by the scanner with a high resolution, however, has a huge data size. Moreover, the image information must be stored for each color-separated set of image data, so the memory for storing the image data needs to be of a large capacity. This situation is the same when the image information of a color original is subjected to special image processing. Specifically, implementation of image processings which increases the image data size, such as resolution conversion, magnification conversion, image gradation conversion, etc., needs storage of a large capacity for storing the image data. The color images handled in a digital color copier of this type, are controlled as color separated image data, and the data amount of a digital image tends to be very large in the pursuit of an improved quality of image. Accordingly, recent machines need a storage device of a greater capacity than that in the conventional machines. Further, digital color copiers, need to store three sets of color separated data, i.e., Y, M and C, and an extra set of data for Bk which is detected from Y, M and C colors, needing about four-fold memory capacity.
Recently, the price of semiconductor memory devices as a large capacity storage device has become lower, yet the memory device of a greater capacity becomes proportionally expensive, giving rise to a big problem even in view of the total product cost of a digital color copier. For this reason, if a digital color copier having high capacity memory devices is attempted to be commercialized, the price becomes very expensive, which hinders the spread onto the market in the present stage.